PROJECT SUMMARY/ABSTRACT While the rapidly evolving nanotechnology has shown promise in electronics, energy, healthcare and many other fields, there is an increasing concern about the adverse health consequences of engineered nanomaterials. In vivo studies have shown that inhaled carbon nanotubes can rapidly enter the lung interstitium to stimulate collagen production and induce progressive interstitial lung fibrosis, which is a fatal and incurable disease with no known effective treatment. To evaluate the toxicity of nanomaterials, animal studies are necessary but costly, time-consuming and facility limited; while the majority of current in vitro models suffer from a series of drawbacks, most importantly, they lack characteristics of in vivo microenvironment, leading to losses of critical in vivo cell phenotypes and responsiveness. There is, therefore, a critical need to develop in vitro models of physiological relevance to provide reliable, rapid and inexpensive methods for toxicology studies and risk assessment of nanomaterials. The extracellular matrix of lung interstitium manifests significant nanoscale topographies, exhibits various degrees of stiffness, and is enriched with interstitial fluids. The physiological breathing movements also provide cyclic mechanical strain. Although the physical (substrate nanotopography and stiffness) and mechanical (fluid-induced forces and mechanical strain) cues critically influence numerous developmental, physiological and pathological processes in vivo and have a profound influence on cell phenotype and function in vitro, there has been no effort reported on integrating these factors into a single platform for toxicology studies. Our hypothesis is that the interstitial fibrotic response to nanomaterials in vitro can be more accurately evaluated in a physiologically relevant microenvironment. Therefore, the objective of this project is to develop an alveolar interstitium model integrated with the physical and mechanical cues of physiological relevance to investigate nanomaterials induced lung fibrogenesis. We have assembled an interdisciplinary research team to carry out nanotoxicology studies both in vivo and in vitro, and provided strong evidence that nanotopography, stiffness and fluidic shear stress have profound influences on cell behavior. Based on the compelling preliminary results, we propose two Specific Aims in this project: (1) dissect substrate nanotopography and stiff modulated human lung fibroblast sensing nanomaterials, and (2) build a microfluidic platform integrated with key physical, mechanical and structural characteristics of lung interstitium to assess nanomaterials induced fibrogenesis. Successful completion of this project will advance our fundamental understanding of physical and mechanical modulation of cell behavior and develops a novel, biomimetic interstitium microenvironment to advances over the ?classic? in vitro cytotoxicity methods. This biomimetic model is expected to fill the knowledge and technology gaps between current in vitro models and animal studies, and potentially promote sustainable development of nanotechnology.